tire

Abstract

To provide a tire that can improve dry grip performance. [Solution] A tire having a tread portion, wherein the tread portion is composed of a rubber composition comprising a rubber component, a filler, and a plasticizer, the rubber component comprising styrene-butadiene rubber, the filler comprising carbon black, and the plasticizer comprising a resin component, wherein when the radius of curvature of the tread portion at the tire equator is R (mm) and the tanδ peak temperature of the rubber composition is T (°C), T is 25.0 or greater and R / T is less than 10.0.

Description

[Technical Field]

[0001] This invention relates to tires. [Background technology]

[0002] To ensure safety and other factors, tires are required to have grip performance, such as dry grip performance, and various types of tires have been developed to meet these requirements (Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-203073 [Overview of the project] [Problems that the invention aims to solve]

[0004] One way to achieve high dry grip performance is to increase the tanδ peak temperature of the tread rubber. However, if the tanδ peak temperature is raised too high, the tread rubber will harden and become glass-like at the tire's operating temperature, raising concerns about slippage during driving.

[0005] The present invention aims to provide a tire that can improve dry grip performance. [Means for solving the problem]

[0006] The present invention relates to a tire having a tread portion, wherein the tread portion is composed of a rubber composition comprising a rubber component, a filler, and a plasticizer, the rubber component comprising styrene-butadiene rubber, the filler comprising carbon black, and the plasticizer comprising a resin component, wherein when the radius of curvature of the tread portion at the tire equator is R (mm) and the tanδ peak temperature of the rubber composition is T (°C), T is 25.0 or greater and R / T is less than 10.0.

Advantages of the Invention

[0007] According to the present invention, there is provided a tire capable of improving dry grip performance.

Brief Description of the Drawings

[0008] [Figure 1] It is a meridian cross-sectional view of a tire according to an embodiment of the present invention. [Figure 2] It is a modification of the tire according to this embodiment. [Figure 3] It is an example of a cross-sectional view by a plane including a tire rotation axis showing a state where the tire is in contact with the road surface (when the crown portion is within the contact surface). [Figure 4] It is an example of a cross-sectional view by a plane including a tire rotation axis showing a state where the tire is in contact with the road surface (when the crown portion extends beyond the contact surface).

Modes for Carrying Out the Invention

[0009] A tire according to an embodiment of the present invention is a tire having a tread portion, wherein the tread portion is composed of a rubber composition containing a rubber component, a filler, and a plasticizer, the rubber component includes styrene-butadiene rubber, the filler includes carbon black, the plasticizer includes a resin component, when the radius of curvature at the tire equator of the tread portion is R (mm) and the tanδ peak temperature of the rubber composition is T (°C), T is 25.0 or more and R / T is less than 10.0.

[0010] Although not intended to be bound by theory, in the tire of the present invention, as a mechanism for improving dry grip performance, for example, it can be considered as follows.

[0011] (1) By blending a rubber component containing styrene-butadiene rubber, a filler containing carbon black, and a plasticizer containing a resin component, heat generation of the tread rubber can be promoted, so it is considered to contribute to the improvement of dry grip performance.

[0012] Furthermore, (2) by restricting the radius of curvature of the tread at the tire equator and reducing the contact area of ​​the tread, the pressure on the tread is increased, and the temperature of the tread rises more easily during driving. This is thought to make it easier to achieve dry grip performance even when using tread rubber with a high tanδ peak temperature.

[0013] It is believed that the combined effect of (1) and (2) above will achieve the remarkable result of improved dry grip performance.

[0014] The amount of plasticizer in the rubber composition relative to 100 parts by mass of rubber component is preferably 120 parts by mass or more, from the viewpoint of promoting heat generation of the tread rubber and further improving grip performance.

[0015] From the viewpoint of promoting heat generation in the tread rubber and further improving grip performance, the resin component content in the plasticizer is preferably 60% by mass or more.

[0016] From an environmental perspective, it is preferable that the resin component includes a sustainable resin.

[0017] The amount of resin component in the aforementioned rubber composition relative to 100 parts by mass of rubber component is preferably 50 parts by mass or more, from the viewpoint of promoting heat generation of the tread rubber and further improving grip performance.

[0018] The amount of acetone extracted from the rubber composition is preferably 30% by mass or more, from the viewpoint of promoting heat generation in the tread rubber and further improving grip performance.

[0019] The total amount of styrene in the aforementioned rubber component is preferably 40% by mass or more, from the viewpoint of promoting heat generation in the tread rubber and further improving grip performance.

[0020] The radius of curvature R is preferably less than 250 mm. By setting R within the above range and reducing the contact area of ​​the tread, the pressure applied to the tread can be increased, which is thought to promote the heating of the tread rubber.

[0021] The total amount of filler in the aforementioned rubber composition relative to 100 parts by mass of rubber component is preferably 100 parts by mass or more, from the viewpoint of promoting heat generation of the tread rubber and further improving grip performance.

[0022] From the viewpoint of further improving grip performance, the tanδ (100°C tanδ) of the rubber composition is preferably 0.40 or higher.

[0023] When the complex modulus of elasticity of the rubber composition at 100°C is 100°CE* (MPa), it is preferable that 100°Ctanδ / 100°CE* is greater than 0.23. It is believed that setting 100°Ctanδ / 100°CE* within the above range contributes to improving dry grip performance, taking into account the heat generation effect due to deformation of the tread.

[0024] The tire according to this embodiment is suitably used as a tire for motorcycles.

[0025] The tread portion has a crown portion located in the center in the tire width direction and a pair of shoulder portions located on the outer side of the crown portion in the tire width direction, and it is preferable that the shoulder portions are made of the rubber composition. It is believed that using the rubber composition in the shoulder portions of the tread portion can improve dry grip performance during cornering and improve cornering speed.

[0026] <Definition> The "tread portion" is a component that includes the part that forms the contact surface of the tire, and in a cross-section of the tire with a plane including the tire rotation axis, if the tire has components that form the tire skeleton using steel or textile materials such as belt layers, belt reinforcement layers, and carcasses, the tread portion is a component that is positioned radially outward from these components.

[0027] "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0028] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0029] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0030] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0031] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. For example, for JATMA it is "Maximum Load Capacity," for ETRTO it is "LOAD CAPACITY," and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0032] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

number

[0033] The "crown portion" is the part of the tread located in the center of the tread, extending outward in the axial direction of the tire beyond ±5% of the tread width from the tire equator, but not reaching the tread edge. However, this excludes the portion of the tread that is provided with an electrically conductive rubber component.

[0034] The "shoulder section" is the part of the tread that is located on the outer side of the crown section in the axial direction of the tire and extends to the edge of the tread.

[0035] "Tread width" is the distance from one tread edge to the other tread edge, which is the outermost edge in the axial direction of the tire, on the tread surface, which is the part of the tread that comes into contact with the road surface.

[0036] "Electrically conductive rubber components" are embedded in the tread of the tire, with a portion exposed to the tire's contact surface, in order to effectively discharge static electricity generated during tire operation. This includes components referred to as base pens.

[0037] "Rubber components of a rubber composition" refer to components that contribute to crosslinking within a rubber composition, and generally have a weight-average molecular weight (Mw) of 10,000 or more.

[0038] "Sustainable resin" refers to a resin component in which some or all of its constituent materials are derived from natural resources such as biomass or recycled materials.

[0039] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. This definition includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. However, it excludes waxes and stearic acid commonly used in the tire industry.

[0040] "Plasticizer content" includes the amount of plasticizer contained in the extensible rubber component that has been pre-stretched with plasticizers such as oil, resin components, and liquid rubber components. The same applies to the oil content, resin component content, and liquid rubber content; for example, if the extensible component is oil, the extensible oil is included in the oil content.

[0041] <Measurement method> The radius of curvature R of the tread portion at the tire equator is determined by the radius of curvature of the arc passing through the three points P1, P2, and P3, where P1 is the intersection point of the tread surface 2A and the tire equator (tire centerline) C in the tire meridian cross-section of the tread portion, and P2 and P3 are points on the tread surface 2A located at a distance of 2.5% of the tread width on both sides of P1 in the tire axial direction (Figures 1 and 2).

[0042] The "amount extracted with acetone" can be determined by immersing each rubber test piece in acetone for 72 hours in accordance with JIS K 6229:2015 to extract soluble components, measuring the mass of each rubber test piece before and after extraction, and using the following formula. (Amount of acetone extracted (mass%)) = {(Mass of rubber test piece before extraction - Mass of rubber test piece after extraction) / (Mass of rubber test piece before extraction)} × 100

[0043] "100℃tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (e.g., GABO's Iplexer series) under the conditions of a temperature of 100℃, a frequency of 10Hz, an initial strain of 10%, a dynamic strain of ±2%, and the extension mode. The sample used for this measurement is a vulcanized rubber composition measuring 20mm in length, 4mm in width, and 1mm in thickness. When preparing the sample by cutting it from a tire, it should be cut from the tread portion so that the tire circumference is the longer side and the tire radius is the thickness direction.

[0044] The "tanδ peak temperature of the rubber composition" is determined by measuring the temperature distribution curve of tanδ in the range of -60°C to 100°C using a dynamic viscoelasticity measuring device (e.g., the Iplexer series from GABO) under conditions of frequency 10 Hz, initial strain 10%, amplitude ±0.5%, and heating rate 2°C / min, and then determining the temperature corresponding to the largest tanδ value in the obtained temperature distribution curve. If there are two points with maximum values ​​of tanδ in the range of -60°C to 100°C, the one with the lower temperature is taken as the tanδ peak temperature. Furthermore, if a temperature distribution curve is obtained in the range of -60°C to 100°C where tanδ gradually decreases with increasing temperature, the tanδ peak temperature is taken as -60°C according to the definition above. The sample for this measurement is prepared in the same manner as in the case of 100°C tanδ.

[0045] "100℃E*" is the complex modulus of elasticity measured using a dynamic viscoelasticity analyzer (e.g., the Iplexer series from GABO) under the conditions of a temperature of 100℃, a frequency of 10Hz, an initial strain of 10%, a dynamic strain of ±2%, and the extension mode. The sample for this measurement is prepared in the same manner as for 100℃tanδ.

[0046] The glass transition temperature (Tg) of SBR is determined in accordance with JIS K 6229:2015 by removing the spreading oil using acetone, and then determining the pure SBR content by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

[0047] "Styrene content" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and13 It is calculated by (13)C-NMR. Component amounts such as "styrene content" are different from physical property values such as complex elastic modulus (E*), and since there are true values that do not depend on the measurement method, it is preferable to use a measurement method with as high precision as possible. In this specification, "thermal decomposition gas chromatography" refers to a method in which a sample is heated by a thermal decomposition device, the individual components contained in the gas-phase components generated by this heating are separated by a separation column, and each isolated component is analyzed. The styrene content is applied to, for example, rubber components having repeating units (styrene units) derived from styrene such as SBR.

[0048] The "vinyl content (amount of 1,2-bonded butadiene units)" is determined by thermal decomposition gas chromatography or NMR measurement ( 1 1H-NMR or 13 13C-NMR). Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "vinyl content", it is preferable to use a measurement method with as high precision as possible. The vinyl content is applied to, for example, rubber components having repeating units derived from butadiene such as SBR and BR.

[0049] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value measured by infrared absorption spectroscopy or NMR measurement ( 1 1H-NMR or 13 13C-NMR) in accordance with JIS K 6239-2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene such as BR. Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "cis content", it is preferable to use a measurement method with as high precision as possible.

[0050] "Total styrene content in rubber components" refers to the total amount of styrene units contained in 100% by mass of the rubber components (by mass%). For each rubber component, the value obtained by multiplying the styrene content (by mass%) by the mass fraction in the rubber components is calculated, and these values ​​are then summed up. Specifically, it is calculated using Σ(styrene content (by mass%) of each styrene-containing rubber × content (by mass%) of each styrene-containing rubber in the rubber components / 100). For example, if the rubber components consist of a first SBR (styrene content: 25% by mass) at 20% by mass, a second SBR (styrene content: 27.5% by mass) at 30% by mass, and BR at 50% by mass, the total styrene content in the rubber components is approximately 13.3% by mass (= (25 × 20 / 100) + (27.5 × 30 / 100) + (0 × 10 / 100)).

[0051] The "weight-average molecular weight (Mw)" can be determined by converting the measured value using gel permeation chromatography (GPC) (for example, the GPC-8000 series from Tosoh Corporation, with a differential refractometer as the detector and TSKgel SuperMultipore HZ-M column from Tosoh Corporation) to a standard polystyrene equivalent. This method is applicable, for example, to SBR, BR, plasticizers, etc.

[0052] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K 6217-2:2017.

[0053] The nitrogen adsorption specific surface area (N2SA) of silica is measured by the BET method in accordance with ASTM D3037-93.

[0054] The "average primary particle diameter" is a value determined by photographing particles with a transmission or scanning electron microscope and taking the arithmetic mean of the particle diameters of 400 particles. If the particle is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter. The average primary particle diameter is applied to silica, carbon black, and other materials.

[0055] The "softening point of the resin component" is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring-type softening point measuring device.

[0056] The procedure for manufacturing a tire, which is one embodiment of the present invention, will be described in detail below. However, the following description is illustrative for explaining the present invention and is not intended to limit the technical scope of the present invention to this scope only.

[0057] [tire] The tire according to this embodiment has a tread portion made of the rubber composition described below. The tread portion may be a single member or a member made up of multiple parts. When the tread portion is a member made up of multiple parts, for example, the tread portion may consist of a crown portion located in the center in the tire axial direction and a pair of shoulder portions located outside the crown portion, but is not limited to this. When the tread portion is a member made up of multiple parts, it is preferable that at least the shoulder portions are made of the rubber composition described below.

[0058] Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. Figure 1 is an example of a planar cross-sectional view of a motorcycle tire including the tire rotation axis (also called the "tire axis") (however, the grooves provided on the tread surface are omitted from the display. The same applies to Figures 2, 3, and 4). The tire 1 comprises a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 arranged on the radially outer side of the carcass 6 and inside the tread portion 2. In the above cross-section, the tread surface 2A of the tread portion 2 that contacts the road surface is convex and curves in an arc outward in the radial direction of the tire. The outer end of the tread surface 2A in the tire axial direction is the tread edge 2e. The tread portion 2 may or may not have grooves.

[0059] In the tread section 2, tread rubber 8 is arranged radially outward from the belt layer 7. In this embodiment, the tread rubber 8 constitutes the area from the outer surface of the belt layer 7 to the tread surface 2A.

[0060] Figure 2 shows a modified example of the tire according to this embodiment. For this modified example, the tire configuration described above may be adopted for parts not described below.

[0061] In Figure 2, the tread rubber 8 is composed of a crown portion 8A centered on the tire equator C, and a pair of shoulder portions 8B adjacent to the crown portion 8A and extending to the tread edge 2e. That is, two types of members, the crown portion 8A and the shoulder portions 8B, are arranged side by side from near the tire equator C toward both sides in the tire axial direction. The crown portion 8A may be further divided. Also, the pair of shoulder portions 8B may each be further divided.

[0062] In Figure 2, the crown portion 8A and the shoulder portion 8B are separated by a normal line 12 drawn on the tread surface 2A. However, the method of separation is not limited to this, and may include, for example, a boundary line that slopes outward or inward in the tire axial direction from the tread surface 2A toward the belt layer 7.

[0063] From the viewpoint of wear resistance, the maximum length of the widthwise curve of the tread surface of the crown portion 8A is preferably 20% or more, more preferably 25% or more, and even more preferably 33% or more, of the widthwise curve length of the entire tread portion 2. Furthermore, from the viewpoint of grip performance, the widthwise curve length of the tread surface of the crown portion 8A is preferably 70% or less, more preferably 60% or less, and even more preferably 55% or less, of the widthwise curve length of the entire tread portion.

[0064] The dividing point (boundary line) between the crown portion 8A and the shoulder portion 8B may be inside the width X of the contact surface (the portion where the tread portion 8 contacts the road surface 100 when filled with normal internal pressure and subjected to normal load), as shown in Figure 3, or it may be outside (see Figure 4). The state shown in Figure 3 is referred to as the "inside the contact surface" state, and the state shown in Figure 4 is referred to as the "outside the contact surface" state. From the viewpoint of preventing step wear caused by differences in the wear resistance of the tread compound, it is preferable that the dividing point be outside the width X.

[0065] From the viewpoint of the effects of the present invention, the radius of curvature R of the tread portion at the tire equatorial plane is preferably less than 250 mm, more preferably less than 225 mm, and even more preferably less than 200 mm. On the other hand, R is preferably greater than 25 mm, more preferably greater than 30 mm, even more preferably greater than 50 mm, even more preferably greater than 70 mm, and particularly preferably greater than 100 mm.

[0066] The tanδ peak temperature T (°C) of the rubber composition constituting the tread is 25.0°C or higher, preferably 25.5°C or higher, and more preferably 26.0°C or higher. On the other hand, from the viewpoint of suppressing tread hardening at the tire's operating temperature, T is preferably 40.0°C or lower, more preferably 37.0°C or lower, even more preferably 34.0°C or lower, and particularly preferably 31.0°C or lower. The tanδ peak temperature of the rubber composition can be appropriately adjusted depending on the type and content of rubber components, plasticizers, etc.

[0067] R / T is less than 10.0, preferably less than 9.5, more preferably less than 9.0, even more preferably less than 8.5, even more preferably less than 8.0, and particularly preferably less than 7.8. It is believed that setting R / T within the above range can optimize the amount of heat generated during tire operation. On the other hand, there is no particular limit to the lower limit of the R / T value, but it is preferably greater than 2.0, more preferably greater than 3.0, even more preferably greater than 4.0, and particularly preferably greater than 5.0.

[0068] From the viewpoint of dry grip performance, the amount of acetone extracted from the rubber composition constituting the tread is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 40% by mass or more. From the viewpoint of durability, it is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0069] From the viewpoint of dry grip performance, the 100°C tanδ of the rubber composition constituting the tread is preferably 0.25 or higher, more preferably 0.28 or higher, even more preferably 0.31 or higher, even more preferably 0.35 or higher, and particularly preferably 0.40 or higher. On the other hand, from the viewpoint of durability performance, it is preferably 0.60 or lower, more preferably 0.55 or lower, and even more preferably 0.50 or lower.

[0070] In this embodiment, 100°C tanδ is an index relating to the heat generation of the rubber composition when driving on a dry road surface. 100°C tanδ can be appropriately adjusted depending on the type and content of the rubber components, fillers, plasticizers, vulcanizing agents, vulcanization accelerators, etc., as described below. For example, it tends to increase with increasing the content of fillers (carbon black, silica, etc.) and plasticizers. 100°C tanδ is measured by the method described above.

[0071] The 100°C E* of the rubber composition constituting the tread is preferably 1.0 MPa or higher, more preferably 1.1 MPa or higher, even more preferably 1.3 MPa or higher, and particularly preferably 1.5 MPa or higher, from the viewpoint of exhibiting restorative force against deformation and improving responsiveness. On the other hand, from the viewpoint of improving heat generation due to deformation of the tread, it is preferably 3.0 MPa or lower, more preferably 2.5 MPa or lower, and even more preferably 2.0 MPa or lower. The 100°C E* of the rubber composition can be appropriately adjusted depending on the type and content of rubber components, plasticizers, etc.

[0072] The 100°C E* / 100°C tanδ is preferably greater than 0.17, more preferably greater than 0.19, even more preferably greater than 0.21, and particularly preferably greater than 0.23. Setting the 100°C tanδ / 100°C E* within the above range is thought to contribute to improving dry grip performance, taking into account the heat generation effect due to tread deformation. On the other hand, there is no particular upper limit to the value of 100°C E* / 100°C tanδ, but it is preferably less than 0.40, more preferably less than 0.35, and even more preferably less than 0.30.

[0073] [Rubber composition] The rubber composition constituting the tread portion according to this embodiment (hereinafter referred to as "the rubber composition according to this embodiment") comprises a rubber component containing styrene-butadiene rubber, a filler containing carbon black, and a plasticizer containing a resin component. All of these can be manufactured using the raw materials described below, according to the required tanδ peak temperature, 100°C tanδ, 100°C E*, acetone extraction amount, etc. The rubber composition according to this embodiment will be described below.

[0074] <Rubber components> The rubber component according to this embodiment contains styrene-butadiene rubber (SBR) as an essential component, and other diene rubbers such as butadiene rubber (BR) can also be suitably used. Furthermore, the rubber component may consist solely of SBR.

[0075] Examples of diene rubbers other than SBR include isoprene rubber, butadiene rubber (BR), styreneisoprene rubber (SIR), styreneisoprenebutadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These diene rubbers may be modified rubbers treated with modifying groups that can interact with fillers such as carbon black or silica, or they may be hydrogenated rubbers in which some of the unsaturated bonds have been hydrogenated. Diene rubbers may be used alone or in combination of two or more. Furthermore, as the diene rubber, stretched rubber that has been pre-stretched using the plasticizers described later may be used.

[0076] The content of diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Alternatively, the rubber component may consist solely of diene rubber.

[0077] (SBR) SBR is not particularly limited and can be any unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), or modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs in which the terminals and / or main chain are modified with a compound having the following functional groups (modifying agent); modified SBRs coupled with tin, silicon compounds, etc. (condensates, branched structures, etc.). Furthermore, hydrogenated versions of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used individually or in combination of two or more types.

[0078] As for SBR, oil-expanded SBR can be used, or non-oil-expanded SBR can be used. When oil-expanded SBR is used, the amount of oil expanded in the SBR, that is, the amount of oil-expanding oil contained in the SBR, is preferably 10 to 50 parts by mass per 100 parts by mass of rubber solids in the SBR.

[0079] Examples of SBRs that can be used in this embodiment include those commercially available from companies such as JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., and ARLANXEO.

[0080] From the viewpoint of the effects of the present invention, the styrene content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 40% by mass or more. On the other hand, the styrene content of SBR is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. The styrene content of SBR is measured by the measurement method described above.

[0081] From the viewpoint of the effects of the present invention, the vinyl content of SBR is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. Furthermore, the vinyl bonding amount of SBR is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. The vinyl content of SBR is measured by the measurement method described above.

[0082] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of SBR is preferably -50°C or higher, more preferably -40°C or higher, and even more preferably -30°C or higher. Furthermore, the Tg of SBR is preferably less than 10°C, more preferably less than 5°C, and even more preferably less than 0°C. The Tg of SBR is measured by the measurement method described above.

[0083] From the viewpoint of grip performance, the weight-average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more, and even more preferably 300,000 or more. Furthermore, from the viewpoint of crosslinking uniformity, the Mw of SBR is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. The Mw of SBR is measured by the measurement method described above.

[0084] From the viewpoint of the effects of the present invention, the SBR content in the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more. On the other hand, there is no particular upper limit to the content.

[0085] (BR) BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. BR may be used alone or in combination of two or more types.

[0086] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., UBE Corporation, and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the measurement method described above.

[0087] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. From the viewpoint of crosslinking uniformity, it is preferably 2,000,000 or less, and more preferably 1,000,000 or less. The Mw of BR is measured by the measurement method described above.

[0088] From the viewpoint of the effects of the present invention, the BR content in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, and particularly preferably 20% by mass or less. Furthermore, there is no particular lower limit to the content, but for example, it can be 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more.

[0089] (Isoprene rubber) As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. Isoprene-based rubbers may be used alone or in combination of two or more types.

[0090] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0091] From the viewpoint of the effects of the present invention, the content of isoprene-based rubber in the rubber component is preferably less than 30% by mass, more preferably less than 20% by mass, even more preferably less than 10% by mass, and particularly preferably less than 5% by mass. Furthermore, there is no particular lower limit to the content.

[0092] From the viewpoint of heat generation, the total styrene content in the rubber component is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and particularly preferably 40% by mass or more. Furthermore, the total styrene content in the rubber component is preferably 55% by mass or less, more preferably 52% by mass or less, and even more preferably 48% by mass or less.

[0093] (Other rubber components) The rubber component may contain other rubber components besides diene rubber, as long as they do not affect the effects of the present invention. Other rubber components besides diene rubber can include crosslinkable rubber components commonly used in the tire industry, such as butyl rubber (IIR), halogenated butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. In addition to the above rubber components, known thermoplastic elastomers may or may not be included. Other rubber components may be used individually or in combination of two or more.

[0094] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0095] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0096] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0097] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0098] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0099] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0100] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0101] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0102] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0103] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0104] For the reasons stated above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0105] <Filler> The rubber composition according to this embodiment includes a filler. The filler contains carbon black as an essential component and may also contain other fillers such as silica. Furthermore, the filler may consist only of carbon black, or it may consist only of carbon black and silica.

[0106] (Carbon Black) The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0107] In addition to the above, from the perspective of life cycle assessment, carbon black made from biomass materials such as lignin, or recycled carbon black refined by thermal decomposition of carbon black-containing products such as tires, may also be used as carbon black.

[0108] In this specification, "recycled carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black, and calcining the crushed material, wherein, according to the thermogravimetric method compliant with JIS K 6226-2:2003, when oxidative combustion occurs by heating in air, the proportion of the mass of ash (ash content), which is the component that does not burn, is 13% by mass or more. In other words, the proportion of the mass (carbon content) lost due to the aforementioned oxidative combustion of recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented as rCB.

[0109] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes usually lacks functional groups on its surface, as referred to in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of Surface Morphology and Chemistry of Pyrolysis Carbon Black and Commercial Carbon Black, Powder Technology 160 (2005) 190-193).

[0110] Recycled carbon black may lack functional groups on its surface, or it may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0111] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LDCarbon.

[0112] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80 m² from the perspective of reinforcing properties. 2 Preferably more than / g, 90m2 More preferably than / g, 100m 2 More preferably than / g, 110m 2 A value exceeding / g is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 250m 2 Preferably less than / g, 220m 2 Less than / g is more preferable, 190m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0113] From the viewpoint of reinforcing properties, the carbon black content per 100 parts by mass of rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 50 parts by mass or more. Furthermore, from the viewpoint of suppressing heat generation, it is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, even more preferably 130 parts by mass or less, and particularly preferably 120 parts by mass or less.

[0114] (silica) The silica used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. Silica may be used alone or in combination of two or more types.

[0115] In this embodiment, from the viewpoint of building a sustainable society, silica derived from biomass materials is preferably used as the silica. Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, filtering, washing with water, drying, and grinding the precipitate of silicon dioxide produced.

[0116] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0117] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.). Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0118] The nitrogen adsorption specific surface area (N2SA) of silica is 110 m², from the perspective of low fuel consumption and wear resistance. 2 Preferably 130m / g or more. 2 More preferably 150m / g or more, 2 More preferably 170m / g or more. 2 A value of 350m or more is particularly preferred. Furthermore, from the viewpoint of low fuel consumption and processability, 350m 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0119] The average primary particle diameter of silica is preferably 24 nm or less, more preferably 22 nm or less, even more preferably 20 nm or less, and particularly preferably 18 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but from the viewpoint of silica dispersibility, it is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. The average primary particle diameter of silica is measured by the measurement method described above.

[0120] When silica is included, its content per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 70 parts by mass or more, from the viewpoint of the effects of the present invention. Furthermore, the content is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, even more preferably 130 parts by mass or less, and particularly preferably 120 parts by mass or less.

[0121] (Other fillers) Other fillers besides silica and carbon black are not particularly limited and may include those commonly used in the tire industry, such as aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, and biochar. These other fillers may be used individually or in combination of two or more.

[0122] From the viewpoint of the effects of the present invention, the total content of filler per 100 parts by mass of rubber component is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably 100 parts by mass or more. Furthermore, from the viewpoint of low fuel consumption performance and elongation at break, it is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 130 parts by mass or less.

[0123] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent used in combination with silica in the tire industry can be used, but examples include mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; and 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. Examples include thioester-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. In particular, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. The silane coupling agent may be used alone or in combination of two or more types.

[0124] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more. Furthermore, from the viewpoint of cost and processability, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

[0125] <Plasticizer> The rubber composition according to this embodiment contains a plasticizer. The plasticizer contains a resin component as an essential component, and may also contain other resin components such as oil.

[0126] In this specification, "plasticizer" refers to a material that imparts plasticity to rubber components, and is a concept that includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. Examples of plasticizers include resin components, oils, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. Plasticizers may be used alone or in combination of two or more types.

[0127] (Resin components) The rubber composition according to this embodiment may also contain a resin component. While not particularly limited, the resin component usable in this embodiment can be one commonly used in the tire industry. Examples include adhesive resins such as terpene resins, rosin resins, dicyclopentadiene resins, aromatic vinyl resins, C9 resins, C5 resins, C5C9 resins, and phenolic resins. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0128] In this embodiment, a sustainable resin is preferably used as the resin component. In this specification, "sustainable resin" refers to a resin component whose constituent components are partly or entirely derived from natural resources such as biomass or recycled materials. That is, a sustainable resin contains raw materials derived from natural resources or recycled materials as constituent components. Furthermore, a sustainable resin may also contain ordinary petroleum-derived raw materials. Examples of resin components containing raw materials derived from natural resources include terpene resins, rosin resins, and aromatic vinyl resins derived from biomass naphtha. Examples of resin components containing recycled materials include C5 resins derived from the pyrolysis oil of tires. Among these, one or more resins selected from the group consisting of terpene resins and rosin resins are preferred as the sustainable resin.

[0129] "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. As the terpene compounds that become monomer components of terpene resins, terpene compounds derived from natural resources can be used. Examples of aromatic compounds that become monomer components of aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that become monomer components of terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0130] "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin, and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc., of the natural resin rosin. As the rosin acid compound, rosin acid compounds derived from natural resources can be used. As rosin-based resins, commercially available products from companies such as Harima Chemicals, Inc., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0131] A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0132] "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0133] A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0134] "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0135] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0136] "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0137] The resin component may include raw materials derived from natural resources such as biomass. Natural resources are not particularly limited and include, for example, sugar, wood, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha. Whether the raw materials of the resin component are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTM D6866-10.

[0138] The resin components containing raw materials derived from natural resources are not particularly limited, but examples include adhesive resins such as terpene resins, rosin resins, dicyclopentadiene resins, aromatic vinyl resins, C9 resins, C5 resins, C5C9 resins, and phenolic resins. Specifically, for example, aromatic vinyl resins derived from biomass naphtha are examples. Furthermore, the terpene compounds constituting terpene resins and the rosin acid compounds constituting rosin resins can be of natural origin.

[0139] The resin components containing recycled raw materials are not particularly limited, but examples include adhesive resins such as terpene resins, rosin resins, dicyclopentadiene resins, aromatic vinyl resins, C9 resins, C5 resins, C5C9 resins, and phenolic resins. Specifically, examples include C5 resins derived from the pyrolysis oil of tires.

[0140] From the viewpoint of grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and filler, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. The softening point of the resin component is measured by the measurement method described above.

[0141] From the viewpoint of the effects of the present invention, the content of the resin component per 100 parts by mass of the rubber component (total amount when multiple resin components are used in combination) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, even more preferably 60 parts by mass or more, even more preferably 65 parts by mass or more, and particularly preferably 70 parts by mass or more. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 110 parts by mass or less, and particularly preferably 100 parts by mass or less.

[0142] (oil) Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0143] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA oils include MES, TDAE, and heavy naphthenic oils. Mineral oil may be used alone or in combination of two or more types.

[0144] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. Vegetable oils may be used individually or in combination of two or more types.

[0145] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0146] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1 When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0147] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0148] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0149] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0150] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol which can be derived from them.

[0151] When oil is included, the content of oil per 100 parts by mass of rubber component is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and particularly preferably 40 parts by mass or more. Furthermore, the content is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0152] (Liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25°C, but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid rubber may be used alone or in combination of two or more types.

[0153] When liquid rubber is included, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Furthermore, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0154] (Ester-based plasticizers) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0155] From the viewpoint of the effects of the present invention, the content of plasticizer per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably 90 parts by mass or more, more preferably 100 parts by mass or more, even more preferably 110 parts by mass or more, and particularly preferably 120 parts by mass or more. Furthermore, the content is preferably 180 parts by mass or less, more preferably 170 parts by mass or less, even more preferably 160 parts by mass or less, and particularly preferably 150 parts by mass or less.

[0156] From the viewpoint of the effects of the present invention, the content of the resin component in the plasticizer is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, and particularly preferably 60% by mass or more. Furthermore, the content is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0157] <Other compounding agents> In addition to rubber components, fillers, and plasticizers, the rubber composition according to this embodiment may appropriately contain compounding agents commonly used in the tire industry, such as vulcanized rubber particles, processing aids, waxes, antioxidants, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0158] Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0159] The vulcanized rubber particles are not particularly limited and may be either unmodified or modified vulcanized rubber particles. Commercially available vulcanized rubber products can be used, for example, those from Lehigh, Muraoka Rubber Industries, and others.

[0160] When vulcanized rubber particles are included, the content per 100 parts by mass of the rubber component can be appropriately adjusted, for example, within a range of more than 1 part by mass and less than 80 parts by mass.

[0161] Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. Processing aids may be used individually or in combination of two or more. Examples of processing aids that can be used are those commercially available from companies such as Schill+Seilacher and Performance Additives.

[0162] When processing aids are included, the content per 100 parts by mass of rubber components is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of exhibiting an effect of improving processability. Furthermore, from the viewpoint of abrasion resistance and fracture strength, it is preferably 10 parts by mass or less, and more preferably 8.0 parts by mass or less.

[0163] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. The wax may be used alone or in combination of two or more types.

[0164] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0165] While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0166] When an anti-aging agent is included, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0167] When stearic acid is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0168] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0169] Sulfur is preferably used as a vulcanizing agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0170] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.7 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0171] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane. These non-sulfur vulcanizing agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis. The vulcanizing agents may be used individually or in combination of two or more.

[0172] The vulcanization accelerator is not particularly limited, but examples include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, and the like. The vulcanization accelerator may be used alone or in combination of two or more. Among these, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred because they more favorably produce the desired effect.

[0173] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, TBBS and CBS are preferred.

[0174] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Among these, MBTS and MBT are preferred.

[0175] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, DPG is preferred.

[0176] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization rate. Furthermore, from the viewpoint of suppressing blooming, the content of the vulcanization accelerator is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0177] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin components, vulcanization accelerators, antioxidants, surfactants, etc.) may be derived from atmospheric carbon dioxide. Methods for obtaining these materials from carbon dioxide include directly converting carbon dioxide, or converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0178] [Manufacturing of rubber compositions and tires] The rubber composition according to this embodiment can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.). The kneading process includes, for example, a base kneading step in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps if desired.

[0179] There are no particular limitations on the mixing conditions, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150-170°C for 3-10 minutes, and in the final mixing process, mixing is performed at 70-110°C for 1-5 minutes. There are no particular limitations on the vulcanization conditions, but for example, vulcanization is performed at 150-200°C for 10-30 minutes.

[0180] A tire according to this embodiment, which has a tread portion made of the aforementioned rubber composition, can be manufactured by conventional methods using the corresponding rubber composition. That is, an unvulcanized rubber composition corresponding to the tread portion obtained by the aforementioned method is extruded in an extruder equipped with a die of a predetermined shape to match the shape of the tread portion, bonded together with other tire components on a tire molding machine, and molded in a conventional method to form an unvulcanized tire. This unvulcanized tire can be manufactured by heating and pressurizing it in a vulcanizing machine to produce the tire according to this embodiment. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be cited.

[0181] [Tire Uses] The tire according to this embodiment can be used for passenger car tires, heavy-duty tires, large SUV tires, motorcycle tires, etc., and is preferably used as a motorcycle tire. When used as a motorcycle tire, the type is not particularly limited and may be either a pneumatic tire or a solid tire, but it is preferable to use it as a pneumatic tire. It can also be used for various applications such as on-road tires, off-road tires, and racing tires. [Examples]

[0182] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. Using the various chemicals shown below, we examined tires having a tread portion obtained according to the formulations in Table 1, and Table 1 shows the results calculated based on the evaluation method described below.

[0183] The various chemicals used in the examples and comparative examples are summarized below. SBR1: SE-6529 manufactured by Sumitomo Chemical Co., Ltd. (Unmodified S-SBR, styrene content: 43% by mass, vinyl content: 57 mol%, Tg: -4℃, Mw: 1.2 million, contains 44 parts by mass of oil-expanding oil per 100 parts by mass of rubber solids) SBR2: Toughden 4850 manufactured by Asahi Kasei Corporation (unmodified S-SBR, styrene content: 40% by mass, vinyl content: 46 mol%, Tg: -25℃, Mw: 350,000, contains 50 parts by mass of oil-expanding oil per 100 parts by mass of rubber solids) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Corporation (cis content: 97 mol%, Mw: 440,000) Carbon Black: Show Black N110 (N2SA: 142m) manufactured by Cabot Japan Co., Ltd. 2 / g) Silica: ULTRASIL VN3 (N2SA: 175m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 18nm) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Industries. Resin component 1: Coresin (pt-butylphenol acetylene resin, softening point: 145°C) manufactured by BASF. Resin component 2: YS Resin PX1150N manufactured by Yasuhara Chemical Co., Ltd. (unhydrogenated polyterpene resin, softening point: 115℃) Wax: Nippon Seiro Co., Ltd. Ozo Ace 0355 (paraffin wax) Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Zinc oxide: Ginrei R manufactured by Toho Zinc Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar NS-G (N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0184] (Examples and Comparative Examples) According to the formulation shown in Table 1, using a 1.7 L sealed Banbury mixer, chemicals other than sulfur and vulcanization accelerators were kneaded for 1 to 10 minutes until the discharge temperature reached 150 to 160 °C to obtain a kneaded product. Next, using a two-roll open mill, sulfur and vulcanization accelerators were added to the kneaded product and kneaded for 4 minutes until the temperature reached 105 °C to obtain an unvulcanized rubber composition. Using the unvulcanized rubber composition, it was molded according to the shape of the tread portion and bonded together with other tire members to produce an unvulcanized tire, which was vulcanized at 170 °C to obtain each test tire described in Table 1. The test tires have the basic structure shown in Figure 1, with the front tire size being 120 / 70ZR17 and the rear tire size being 180 / 55ZR17.

[0185] <Measurement of acetone extraction amount> For the rubber test pieces prepared by cutting from the tread portion of each test tire, they were immersed in acetone for 72 hours in accordance with JIS K 6229:2015 to extract soluble components, and the mass of each rubber test piece before and after extraction was measured. The acetone extraction amount was calculated by the following formula. (Acetone extraction amount (mass %)) = {(Mass of rubber test piece before extraction - Mass of rubber test piece after extraction) / (Mass of rubber test piece before extraction)} × 100

[0186] <Measurement of tanδ peak temperature> For each vulcanized rubber test piece prepared by cutting from the tread portion of each test tire with a length of 20 mm × width of 4 mm × thickness of 1 mm such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, using a dynamic viscoelasticity measuring device (Iplexer series manufactured by GABO), a temperature distribution curve of tanδ from -60 to 100 °C was measured under the conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a heating rate of 2 °C / min. The temperature corresponding to the largest tanδ value in the obtained temperature distribution curve was taken as the tanδ peak temperature.

[0187] <Measurement of 100tanδ and 100 °C E*> Each vulcanized rubber test piece, cut from the tread of each test tire to a length of 20 mm, width of 4 mm, and thickness of 1 mm, with the tire circumference as the longer side and the tire radius as the thickness direction, will be measured using a dynamic viscoelasticity measuring device (GABO's Iplexer series) under the conditions of a temperature of 100°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2%, and the extension mode. The loss tangent tanδ and complex modulus E* will be measured.

[0188] <Dry grip performance> Each test tire is mounted on a standard rim and fitted to the rear wheel of a test vehicle (a large motorcycle with a displacement of 1000cc) under an internal pressure of 200kPa. This test vehicle is driven at 100km / h on a dry asphalt test course, and the control stability is subjectively evaluated by the test driver. The evaluation is given on an integer scale from 1 to 5 points, with higher scores indicating superior steering control stability. The total scores of 20 test drivers are calculated. The total score of the benchmark comparison (Comparative Example 2) is converted to a baseline value (100), and the evaluation results of each test tire are indexed and displayed in proportion to the total score. A higher number indicates better dry grip performance.

[0189] [Table 1]

[0190] <Embodiment> Examples of embodiments of the present invention are shown below.

[0191] [1] A tire having a tread portion, wherein the tread portion is composed of a rubber composition comprising a rubber component, a filler, and a plasticizer, the rubber component comprising styrene-butadiene rubber, the filler comprising carbon black, and the plasticizer comprising a resin component, wherein when the radius of curvature of the tread portion at the tire equator is R (mm) and the tanδ peak temperature of the rubber composition is T (°C), T is 25.0 or more, preferably 26.0 or more, and R / T is less than 10.0, preferably less than 9.0, more preferably less than 8.0. [2] The tire according to [1] above, wherein the content of plasticizer in the rubber composition is 120 parts by mass or more per 100 parts by mass of rubber component. [3] The tire according to [1] or [2] above, wherein the resin component content in the plasticizer is 60% by mass or more. [4] The tire according to any one of [1] to [3] above, wherein the resin component includes a sustainable resin. [5] The tire according to any one of [1] to [4] above, wherein the content of the resin component in the rubber composition is 50 parts by mass or more, preferably 60 parts by mass or more, and more preferably 70 parts by mass or more, relative to 100 parts by mass of the rubber component. [6] The tire according to any one of [1] to [5] above, wherein the amount of acetone extracted from the rubber composition is 30% by mass or more. [7] The tire according to any one of [1] to [5] above, wherein the amount of acetone extracted from the rubber composition is 40% by mass or more. [8] A tire according to any one of [1] to [7] above, wherein the total amount of styrene in the rubber component is 40% by mass or more. [9] A tire as described in any of [1] to [8] above, wherein the R is less than 250.

[10] A tire as described in any of [1] to [8] above, wherein the R is less than 200.

[11] The tire according to any one of [1] to

[10] above, wherein the total content of filler relative to 100 parts by mass of rubber component in the rubber composition is 100 parts by mass or more.

[12] The tire according to any one of [1] to

[11] above, wherein the tanδ (100°C tanδ) of the rubber composition at 100°C is 0.40 or more.

[13] The tire according to

[12] above, wherein when the complex modulus of elasticity of the rubber composition at 100°C is 100°CE* (MPa), 100°Ctanδ / 100°CE* is greater than 0.23.

[14] A tire for motorcycles, as described in any of [1] to

[13] above.

[15] The tire according to

[14] above, wherein the tread portion has a crown portion located in the center in the tire width direction and a pair of shoulder portions located on the outer side of the crown portion in the tire width direction, and the shoulder portions are made of the rubber composition. [Explanation of symbols]

[0192] 1 tire 2 Tread section 2A Tread surface 2e tread edge 3. Sidewall section 4. Bead section 5 Bead core 6 Carcass 7 Belt layer 8 Tread Rubber 8A Crown section 8B Shoulder section 100 road surface C Tire equator (tire centerline) X Width of the contact surface

Claims

1. A tire having a tread portion, The tread portion is composed of a rubber composition containing rubber components, fillers, and plasticizers. The aforementioned rubber component includes styrene-butadiene rubber. The filler contains carbon black, The aforementioned plasticizer contains a resin component, A tire in which, when R (mm) is the radius of curvature of the tread portion at the tire equator and T (°C) is the tanδ peak temperature of the rubber composition, T is 25.0 or greater and R / T is less than 10.

0.

2. The tire according to claim 1, wherein the content of plasticizer in the rubber composition is 120 parts by mass or more per 100 parts by mass of rubber component.

3. The tire according to claim 1 or 2, wherein the resin component content in the plasticizer is 60% by mass or more.

4. The tire according to claim 1 or 2, wherein the resin component includes a sustainable resin.

5. The tire according to claim 1 or 2, wherein the content of the resin component in the rubber composition is 50 parts by mass or more relative to 100 parts by mass of the rubber component.

6. The tire according to claim 1 or 2, wherein the amount of acetone extracted from the rubber composition is 30% by mass or more.

7. The tire according to claim 1 or 2, wherein the amount of acetone extracted from the rubber composition is 40% by mass or more.

8. The tire according to claim 1 or 2, wherein the total amount of styrene in the rubber component is 40% by mass or more.

9. The tire according to claim 1 or 2, wherein the R is less than 250.

10. The tire according to claim 1 or 2, wherein the R is less than 200.

11. The tire according to claim 1 or 2, wherein the total content of filler relative to 100 parts by mass of rubber component in the rubber composition is 100 parts by mass or more.

12. The tire according to claim 1 or 2, wherein the tanδ (100°C tanδ) of the rubber composition at 100°C is 0.40 or more.

13. The tire according to claim 12, wherein, when the complex modulus of elasticity of the rubber composition at 100°C is 100°CE* (MPa), 100°C tanδ / 100°CE* is greater than 0.

23.

14. A tire for a motorcycle, as described in claim 1 or 2.

15. The tread portion has a crown portion located in the center in the tire width direction and a pair of shoulder portions located on the outer side of the crown portion in the tire width direction. The tire according to claim 14, wherein the shoulder portion is made of the rubber composition.

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